Bacteria in Healthy Placentas

Contrary to the prevailing idea of a “sterile” intrauterine environment, Aagaard and coauthors demonstrated the consistent presence of a microbiome in placentas from healthy pregnancies. This microbiome was consistently different from those reported in other parts of the body, including the skin and urogenital tract. The placental microbiome was most similar to that of the oral cavity, but the clinical implications of this finding remain to be explored. In addition, the authors identified associations between the composition of the placental microbiome and a history of remote antenatal infection, as well as preterm birth, raising the possibility that the placental microbiome may play a role in these events.